Flow behavior and dynamic recrystallization of a power metallurgy nickel-based superalloy during hot compression in (γ plus γ′)-phase region

Flow behavior and dynamic recrystallization of a powder metallurgy EP962NP nickel-based superalloy in the (gamma + gamma')-phase region have been investigated under the isothermal compression at 1075-1150 degrees C with strain rate of 0.0005-0.1 s(-1). The results show that predicated solvus temperature of gamma' precipitates is as high as similar to 1196 degrees C. Flow stress behavior of experimental alloy exhibits typical characteristics of dynamic recrystallization (DRX) and can be well described by hyperbolic-sine Arrhenius-type model with a higher thermal deformation activation energy of 1181.7 kJ/mol. Discontinuous dynamic recrystallization can be identified as a dominant nucleation mechanism for DRX of the alloy, as evidenced by the prevalent observation of necklace structures. In addition, the refined recrystallized gamma grains can be obtained with a higher strain rate due to the increasing deformation stored energy. During hot compression, the morphology of primary gamma' transforms from micron-scale irregular blocks to nano-scale spherical precipitates via the dissolution and re-precipitation process. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The flow behavior and dynamic recrystallization of a powder metallurgy EP962NP nickel-based superalloy in the (gamma + gamma')-phase region have been investigated, showing typical characteristics of dynamic recrystallization behavior and discontinuous dynamic recrystallization mechanism with prevalent observation of necklace structures. The refined recrystallized gamma grains can be obtained with a higher strain rate, and primary gamma' morphology transforms from micron-scale irregular blocks to nano-scale spherical precipitates via dissolution and re-precipitation process during hot compression.